U.S. Pat. No. 4,568,149 discloses that a shading member composed of, for example, aluminum may be provided between adjacent color filters (that is, between adjacent picture elements) on a transparent electrode formed of indium-tin-oxide (hereinafter abbreviated to ITO) or a mixture of indium oxide (In.sub.2 O.sub.3) and tin oxide (SnO.sub.2).
The method taught by this patent requires a large number of manufacturing steps, including a film forming step for making a transparent electrode, a film forming step for making a shading member, and an etching step for making the shading member. Moreover, the shading member projecting from the transparent electrode makes an injection of liquid crystal material difficult. Further, as the shading member is formed of a metal such as aluminum, the light from a back light is reflected by the shading member, and enters the thin film transistor provided on the substrate which faces the substrate on which the shading member is disposed. This may adversely affect the characteristics of the thin film transistor.
U.S. Pat. No. 4,733,948 discloses that a shading member composed of, for example, aluminum may be provided at a position between adjacent color filters on a transparent electrode disposed on one of two opposing substrates and facing a thin film transistor disposed on the other substrate.
The methods disclosed in this patent, as is the case for U.S. Pat. No. 4,568,149, requires a large number of steps including a film forming step for making a transparent electrode, a film forming step for making a shading member, and an etching step for forming the shading member.
Japanese Published Unexamined Patent Application (PUPA) 62-135809 discloses that a photoresist may be applied to a transparent conductive film composed of ITO which is provided on a transparent substrate, followed by exposure and development, thereby patterning the photoresist. Then the part of the transparent conductive film not coated with the photoresist is removed by etching, and using the patterned photoresist as it is as a masking material, a shading layer is formed of metal oxides in the region where no transparent conductive film is provided on the substrate.
The method disclosed in PUPA 62-135809 does not require the etching step for forming the shading layer, but does require the etching step for forming a transparent electrode, and also necessitates a film forming step for forming a transparent electrode and another film forming step for forming a shading layer.
Japanese PUPA 63-74033 discloses applying a photoresist on an ITO film; forming a pattern by exposure and development through a mask, then removing the part of the ITO film not coated with the photoresist by etching, and reducing the remaining ITO film as it is with the photorsist deposited thereon in a hydrogen plasma, thereby lowering the resistance of each side of the ITO film which has been patterned.
PUPA 63-74033 relates to the reduction of and ITO electrode, but is intended to lower the resistance of the ITO electrode, and does not suggest the use of the material obtained by reducing ITO as a shading material.